Question

已知函数f(x)=(x^2+x+1)/(x^2+1),若f(-a)=1/3,则f(a)=

Answer 1

解：f(x)=(x^2+x+1)/(x^2+1)=1+x/(x^2+1)
故f(-a)=1-a/(a^2+1)=1/3,
得a/(a^2+1)=2/3

因此f(a)=1+a/(a^2+1)=1+2/3=5/3

Answer 2

结果是5×根号2 去http://www.jyeoo.com/math/search?c=0&q=%E5%B7%B2%E7%9F%A5%E5%87%BD%E6%95%B0f%28x%29%3D%28x%5E2%2Bx%2B1%29%2F%28x%5E2%2B1%29%2C%E8%8B%A5f%28-a%29%3D1%2F3%2C%E5%88%99f%28a%29%3D 看